| The Tunnel Boring Machine(TBM)is a large-scale equipment dedicated to tunnel construction.As the core component of the entire TBM,the TBM cutterhead has the function of excavating rock and stabilizing the face.During the working process,TBM cutters are subjected to various complex random loads due to the complexity of rock mass geology,the variability of operating conditions and the randomness of rock fragmentation.Under the repeated action of these random loads,the cutterhead will produce fatigue failure,which seriously affects the working efficiency and service life of the TBM.In order to ensure the efficiency of TBM work and the progress of the project,it is especially important to analyze the fatigue life of the TBM cutterhead.This paper focuses on the fatigue life of the TBM cutterhead,comprehensively analyzes the cutterhead fatigue mechanism and failure process,cutterhead load types and working conditions,further clarifies the basic method and key steps of cutterhead fatigue analysis,and identified the way to achieve the key steps.Finally,the fatigue life of TBM cutterhead was estimated.The main research contents of the thesis include:(1)The formation of the rock breaking system model.Based on the cutterhead design drawing and the selected actual stratum,a simplified 3D model and rock model of the cutterhead were constructed through SolidWorks.And built a rock breaking system model.(2)Acquisition of the original load time history of the TBM cutterhead.The rock breaking process of cutterhead system under different working conditions is simulated by using dynamic simulation software ADAMS.The original load time history of the TBM cutterhead is obtained by extracting the load time history of all the hobs on the cutterhead.(3)Compilation of the load spectrum of the TBM cutterhead.Statistical analysis was carried out on the original load time history of the TBM cutterhead.The MATLAB programming method is used to compress the original load data and count the Rain flow counting method to obtain a load spectrum that can be used for actual loading.With the help of the probability density function of the two-parameter Weibull distribution,the statistical analysis of the load data is extrapolated,and a comprehensive TBM cutter eight-level load spectrum is compiled.(4)Determination of the dangerous position of the TBM cutterhead.Since the fatigue damage of the cutterhead structure generally appears at the maximum position of the local stress,the ANSYS Workbench is used in this paper to obtain the stress distribution of the cutterhead structure by applying a load on the bearing surfaces of all the cutter holders on the cutterhead,thereby obtaining the dangerous position of the component.Prepare for late cutterhead fatigue analysis.(5)Calculation of the fatigue life of the TBM cutterhead.The S-N curve of the cutterhead was obtained by correcting the S-N curve of the material.The fatigue life prediction of the TBM cutterhead was carried out by theoretical calculation and quasi-static fatigue analysis.The results show that the right flange weld of the TBM cutterhead may be the first to cause fatigue damage,which is a dangerous area.The forecast results are consistent with the actual results.Cutter fatigue life estimation also provides guidance for cutter protection and structural design. |
